2400M/4400M Pneumatic Space Saver Indicating Relay
The AMOT 2400M and 4400M indicating relays are compact visual status indicators designed for failsafe pneumatic or hydro-mechanical systems. Commonly used in engine panels, ESD systems, and sequencing circuits, they provide immediate red/green indication when a monitored process condition—such as pressure, temperature, or vibration—trips a sensing device.
Both models function as 3-way spool valves and have only one moving part for long-term reliability. A wide viewing angle ensures high visibility in low-light or high-vibration environments.
Key Differences
2400M: Anodized (Gulfproofed) aluminum 4400M: 316 stainless steel for corrosive or offshore use
Technical Highlights
- Operating range: –26°C to 93°C (–15°F to 200°F)
- Flow coefficient: Cv = 0.50 (relay), Cv = 0.56 (bypass)
- Operating pressure: 20–125 psi (w/o trip lockout), 30–60 psi (w/ trip lockout)
- Seal options: Viton or Viton/Teflon
- Mounting: Panel mount with NPT or BSP threads
Optional Features
- Trip port lockout (holds tripped state until reset)
- IN port bypass (test sensors without triggering shutdown)
- Visible trip tape for enhanced indication
Ideal for diesel engines, compressors, gearboxes, and other systems requiring reliable first-out indication.
| Operating temperature: | -26 to 93°C | 15 to 200°F | |
| Flow coefficient: | Indicating relay | Kv = 0.43 | Cv = 0.50 |
| Internal orifice | Kv = 0.017 | Cv = 0.02 | |
| IN Port bypass valve | Kv = 0.48 | Cv = 0.56 | |
| Operating pressure: | Indicating relay w/o trip port lockout | 20 - 125 psi | 140 - 860 kPa |
| Indicating relay with trip port lockout | 30 - 60 psi | 205 - 410 kPa |
- Pneumatic Control Panels
- Compressor Control Panels
- Engine Control Panels
- Wellhead Control Panels
- First-Out Indication
- Fail-Safe Systems
- Sequencing Systems
AMOT Indicating Relays are differential force operated 3-way spool valves with a side viewing window, a special Red (striped) - Green spool and 4 ports. Usually one 2400/4400M is connected to a condition-sensing device. The sensing devices are normally closed 2-way valves which detect undesirable temperatures, pressures, vibration, liquid levels, etc. Sensing valves are connected to the “TRIP” port of each Indicating Relay, and pressure is introduced at the “IN” port. As supply air or gas enters the “IN” port it shifts the spool initially to the tripped position (Red) and continues through an internal orifice out to the sensor. If the sensor is in its satisfied condition (closed), the large end of the piston will be pressurized and the piston will shift into the safe (Green) position.
